Tube forming apparatus



TUBE FORMFENG APPARATUS Original Filed Oct. 51, 1945 2 Sheets-Sheet l INVENTORS ATTEI RN EYS May 18, 1954 D. E. HERVEY ETAL TUBE FORMING APPARATUS 2 Sheets-$heet 2 Original Filed Oct.

Fa w'di Patented May 18, 1954 UNITED .11}

OFFICE TUBE FORMING APPARATUS Original application Octo 625,766. Divided and 2, 1951, Serial No. 213

3 Claims. 1

This invention relates to an apparatus and method for forming articles from plywood and laminated materials.

This invention is a divisional application of our copending application, Serial No. 625,765, filed October 31, 1945, now Patent No. 2,549,810.

Heretofore tubes or tubing that have been formed from plywood have consisted of either one complete revolution of the plywood with the two edges butted up against each other or where several thicknesses of the plywood are joined together, each layer is a separate piece and is bent around the preceding one and the surfaces are glued together.

The surfaces of the respective pieces of this old method are not moved sidewise or lengthwise during the laying up process, and each piece of plywood applied requires a separate laying up process.

An object of this invention, therefore, is to provide a method for making tubing and other articles, wherein one piece of plywood or laminated material makes more than one complete revolution and, the face of one portion of the piece of plywood is glued to the face of another portion of the same piece.

It is to be understood that this structure when completed need not be circular in cross-section but could be any number of shapes or sizes made up of many longitudinal sections.

In some instances when the method is employed, the plywood or laminated material needs to be lapped over on itself only a very short distance while in others the plywood or laminated material may consist of several layers wrapped over upon themselves two, three or more times.

One of the chief advantages of this invention is that prefabricated sheets which do not shrink or swell appreciably, which are flat and free from buckles, which are strong and not apt to break in handling, which may make use of low grade and low price materials, and which will often reduce other costs of construction, may be made directly into the finished product by multiple wrapping and by drawing these wrappings tight by turning one or both the cover placed over the wrappings or the core, over which the wrap- -ings are formed and thereby providing a substantial bond in one simple operation.

With the above and other objects and advantages in view, the invention consists of the novel details of construction, arrangement and com bination of parts more fully hereinafter described, claiined and illustrated in the accompanying drawings, in which:

her 31, 1945, Serial No. sglgis application March Figure 1 is an elevational view of a device used in carrying out the method of forming the tubing shown, partly in section and partly broken away;

Figure 2 is a sectional view on the line 2-4 of Figure 1, with the tubing in loosely wrapped formation;

Figure 3 is the same after pressure has been applied to the tubing to form and bind it into a unitary structure;

Figure 4 is a sectional view of another form of device for carrying out the method;

Figure 5 is a sectional view on the line 5-5 of Figure 4;

Figure 6 is a sectional view of a device wherein internal pressure is used to form the tubing; and

Figure 7 is a sectional view of a device wherein both internal and external pressure is used to form the tubing.

In carrying out the method embodying the invention as shown in Figures 1 to 3, inclusive, where exact inside dimensions are desirable, the plywood or laminated material H! after it has had adhesive applied to one or both faces thereof is wrapped around a longitudinally split core l2 in a counterclockwise manner until it is all wrapped on the core 1 2 and upon itself to provide a bond between the surfaces. To provide maximum retention of adhesive it should be wrapped loosely at first, as shown in Figure 2. In order to provide a better bond and eliminate any voids that might occur in the wrapping process, a longitudinally split cover or outside sectional tubular casing i l is positioned on the outer surface of the plywood H3 and is gradually diminished in size, while the core and material are continuously turned in a counterclockwise or clockwise manner, by means of the tighteners i6, secured to the casing it on the opposite surfaces of the free longitudinal edges thereof, and adjacent each end thereof and the sections 18 and 20 of the tubing M- are connected by hinges 22.

This action brings pressure to bear on the entire outer surface of the plywood l0, causing the surface of each wrapping thereof to move, slip or skid with relation to each other.

The cover is retained in position until the adhesive is partially or completely set, during which time heat may be applied directly to the material by means of high frequency induction of an electrical current by means not shown. In order to decrease the time necessary for the adhesive to bond the layers, the cover and the core may be formed as the two electrodes of a high frequency heating unit to heat and set the ad- 3 hesive by induction. This apparatus is not shown in the drawings.

Where exact outside dimensions are required or desired, the cover or casing M is adjusted to the desired dimensions, and the cover, though shown tubular in cross-section, can assume any desired shape, and is held in this position while the plywood H3 or laminated material is internally expanded by means of an inflatable bag 25 which is placed interiorly of the longitudinally split core [2 and is inflated by means of the air valve 26, causing internal pressure on the plywood rather than external pressure, as previously described, as in the previous method, and the internal pressure is retained until the adhesive is partially or completely set.

In carrying out the method shown in Figures 4 and 5, the apparatus 3? is employed. The apparatus comprises an elongated base 32 having vertical ends as and diametrically opposed sup ports 36 formed integrally with the base relatively spaced with relation to each other and internally of the ends Ed.

The base 32 is provided with a raised platform portion 33 which is integral with the base having the depending sides as, and the platform 33 is provided with grooves ii! transversely thereof to receive the dovetail blocks 44 slidably therein.

Secured to the blocks 44 by means of fasteners 45 are the semicircular hollow sections 48 and 50, respectively, which abut at their inner faces to provide the casing 52.

Mounted for sliding movement in the supports 35 is the sectional mandrel -5 which is keyed together at the joint 55 by means of the key 53. Secured to the outer ends of the mandrel 55 by fasteners 53 are the wheels 52 by means of which the mandrel can be rotated, the purpose of which will be later explained.

The platform is provided at its outer sides with diametrically opposed supports 64 which are. adapted to threadably receive the pressure screws 55 which are controlled by the wheels 53. The mandrel is provided with circular grooves lfl adjacent to its ends in which the catch or latch '52 engages to retain. the mandrel in position in the supports and a second set of grooves is internally of the grooves it permit steam or other hearing medium to enter the mandrel 5 by means of the inlet pipes id. slide valve E8 retains the heating medium within the mandrel 54. When it is desired to move the mandrel 54 longitudinally of the casing 52, the screws iii! are threaded into the threaded bores 32 in the ends of the mandrel 54 longitudinally of the casing 52, by means of the wheels 86 secured thereto by pins 85. When the wheels 84 are rotated in the opposite direction, the mandrel will be withdrawn from the casing it]. One of the bores 82 is shown in the left side of Figure 4.

When this apparatus is used, the end of the plywood it is mounted in the longitudinal slot 88 in the mandrel 54, which is then turned to wrap the plywood around the mandrel 54, and the casing is moved to envelope the plywood by means of the pressure screws Bit, and the sections of the casing 52 are closed until their inner faces approach or abut, while at the same time the mandrel is turned again to wrap the plywood tightly. Then a heat medium is app ied to the mandrel 54 by means of the inlet pipe 16 and to the casing sections 18 and 5 3 by means of an inlet 93. Thus, external pressure, heat and rotary movement of the mandrel is effected to bind the tubing into a unitary structure as previously described.

A spring pressed In Figure 6, a hollow tubular casing 92 is employed having a base 94 secured to a support 96 by means of fasteners 98. In this instance, steam is admitted to the casing 92 by the inlet pipe 569 and an inflatable bag I82 is positioned within a core its on which the plywood I0 is wrapped.

Thus, heat and internal pressure is used in this method of forming the tubing.

In Figure 7, an inflatable bag I0?) is employed with the structure previously described in Figures 4 and5, and includes the semicircular hollow sections 48 and 5B, pressure screws 56 and steam inlets 9c, the other elements remaining as previously described.

Thus, internal and external pressure is employed as well as heat.

Another method in forming the tubing is to employ the structure shown in Figures 1 to 3 and turn the cover while the bag is being inflated, also both core and cover may be rotated in opposite directions.

In order to reduce the size of the pieces of plywood or laminated material and to effect savings in time and labor and to accomplish different forms or thicker walls, two or more pieces may be introduced into the apparatus when forming the tubing.

It is believed that the method of the invention and the manner in which it is carried out will be apparent to those skilled in the art, and it is to be understood that the forms of apparatus shown and described herein are merely used for purposes of illustration, since other apparatus may be employed to carry out the method and the invention is only to be limited by the scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a tube forming apparatus, an elongated base having vertically disposed ends, a pair of vertically disposed, spaced, parallel supports extending upwardly from said base and spaced inwardly from said ends, said base being provided with a raised platform. said platform being provided with spaced, parallel grooves, dovetail blocks slidably arranged in said grooves, a semicircular hollow section secured to each of said blocks, said sections having their inner faces abutting to provide a hollow casing, a mandrel slidably mounted in said supports and projecting into said casing for receiving a wrapping of laminated material thereon, manually operable wheels for rotating said mandrel, pressure screws arranged in engagement with said sections for adjusting the latter, manually operable wheels for adjusting said pressure screws, and means for directing a heating medium to the interior of said mandrel.

2. In a tube forming apparatus. an elongated base having vertically disposed ends, a pair of vertically disposed, spaced, parallel supports extending upwardly from said base and spaced inwardly from said ends, said base being provided 7 with a raised platform, said platform being provided with spaced, parallel grooves, dovetail blocks slidably arranged in said grooves, a semicircular hollow section secured to each of said blocks, said sections having their inner faces abutting toprovide a hollow casing, said casing adapted to receive therein a wrapping of laminated material, an inflatable bag arranged interiorly of said laminated material, and manually operable means for adjusting the sections of said casing.

3. A tube forming apparatus comprising a base having vertically disposed ends, a pair of supports extending upwardly from said base and spaced. inwardly from said ends, said base being provided with a platform, said platform being provided with grooves, dovetail blocks slidably arranged in said grooves, a hollow sectien ee cured to each of said. blocks, said sections having their inner faees abutting to provide a hollow casing, a mandrel slidably mounted in said supports and projecting into said casing for receiving a wrapping of laminated material thereon, manually operable wheels for rotating said mandrel, pressure screws arranged in engagement with said sections for adjusting the latter,

manually operable Wheels for adjusting said pressure screws, and means for directing a heating medium to the interior of said mandrel.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,370,391 Wright Mar. 1, 1921 1,840,489 Denmire Jan. 12, 1932 2,296,781 Farny Sept. 22, 1942 2,352,533 Goldman June 27, 1944 2,388,541 Henderson Nov. 6, 1945 2,411,542 Ilch Nov. 26, 1946 2,449,526 Dunne et a1. Sept. 14, 1948 

